Many conventional residential heating and cooling systems include a disposable filter. These filters include a frame, a fibrous filter material, and a mesh screen or the like that supports the filter material. After a period of use, these filters become dirty or clogged and must be replaced. This is accomplished by replacing the entire filter assembly with a new filter and discarding the old one. Depending on the use of the filter, replacement may be required several times a year. Because the frame and screen are discarded with the assembly even though it is only the filter material that is no longer functional, there is unnecessary waste and cost associated with such filters. In addition, because these filters are rather bulky, they are often purchased as they are needed rather than keeping a large supply on hand. Because purchasing a new filter is not always convenient, replacement can be delayed resulting in reduced system performance.
Conventional filters are typically formed from a soft, limp, flexible material that lacks sufficient structural integrity to counteract an applied force. As a result, such filters, when pleated, do not significantly recover after being expanded and do not significantly expand after being collapsed. In addition, such filters do not expand with uniform pleat spacing. Consequently, if one attempts to install such a pleated filter in a frame having ribs designed to mate with the pleats and thereby maintain equal spacing and provide additional support for the filter, it is difficult to match the pleats of the filter with the ribs. Such filters must therefore include a secondary support structure to ensure uniform spacing of the pleats during the installation process. Such support structures, however, add to the material and manufacturing cost of such filters.
Filter assemblies with frames and removable filter elements are known in the prior art. U.S. Pat. No. 6,033,453 (Weddell, III), for example, discloses a reusable frame support rack for supporting and retaining an outstretched, replaceable pleated media filter core. The frame includes a pair of longitudinal angles extending between a pair of transverse angles which carry a flat expanded metal support or reinforcement system.